Strike the 'T' key to sort messages by thread, strike the 'U' key to sort them unthreaded again, just like the 'G' key switches to Grouped By Sort view
Add-on for Thunderbird that replaces the built-in notifications with OS native ones. It supports most Linux Desktop Environments as well as Windows 8.1/10.
Tategaki Requires Restart
Tategaki allows vertical writing-mode on mail compose window.
Sort and Search Customization Dialogs Requires Restart
Sort and search for buttons in (any) toolbar customization dialog
Classic Password Editor Requires Restart
Adds the ability to create and edit entries in the password manager.
QuickFolders (Tabbed Folders) Requires Restart
The "Swiss army knife" of folders. Turn your favorites into tabs - open folders and subfolders, move mails without scrolling around or searching. powerful + easy.
See new mail at a glance after automatic filtering - supports quickFilters addon!
Dorando keyconfig Requires Restart
A modified Dorando's addon to rebind keyboard shortcuts. It is designed to be a drop-in replacement, keeping your old settings. (See details for upgrade instructions.)
Theme Font & Size Changer lets you change the global font size and font family used for the user interface in Firefox. Design your browser with your favorite font.
This extension makes browsing for extensions easier at addons.mozilla.org. It fixes incorrect information about some extensions being not available for SeaMonkey and adds links to the Add-on Converter where needed.
Enhanced Priority Display Requires Restart
Enhanced thread pane display of message priorities.
Adds icons to buttons and/or menus.
'Classic Toolbar Buttons' add-on restores old toolbar button ui (known from Fx 4-7s small view, Fx 4-12s large view & Tb 5-14) for current Firefox, Thunderbird and Seamonkey versions.
Beta builds on versions page!
GNOMErunner Options Requires Restart
Allows to customize GNOMErunner theme
Makes every page to have light text on dark background (exact colors are customizable)
Firefox version is here: https://addons.mozilla.org/firefox/addon/dark-background-light-text/
Password Tags Requires Restart
Adds metadata and sortable tags to the password manager.
Menu Wizard Requires Restart
Customize menus : Helps removing, moving and renaming menus and menu items
Colorize important menu for ease of use! (use Style (CSS))
Change or disable any of used keyboard shortcuts
Support: Firefox, Thunderbird and SeaMonkey
Simple Locale Switcher Requires Restart
An easier management of the user interface language
Restores version numbers for all installed add-ons inside Add-on Manager on Firefox, Thunderbird and Seamonkey.
Active Stop Button Requires Restart
Stop gif animation with button, context menu or Esc key
Stylish-Custom Requires Restart
custom additions to Stylish extension